The present invention relates to an apparatus for automatically controlling chasers for use in automatic threading machines to automatically form a threaded portion having predetermined taper and length at the end of a pipe or like tube on the outer peripheral surface thereof.
Ideally, it is desired that automatic threading machines satisfy the following requirements.
First, they must be easily adjustable to form a threaded portion of predetermined taper and length.
Second, they must be capable of threading a desired number of pipes to form uniform threaded portions with high accuracy.
Third, they must be easily operable even by unskilled persons.
Conventionally, in threading the end of a pipe to form an external threaded portion having the desired taper and length, the chasers are slowly moved in centrifugal direction by manually operating the die head to control the degree of engagement of the chasers and to thereby give the desired taper to the threaded portion, while the chasers are being advanced to thread the pipe over the specified length. Accordingly, the operation invariably requires a skilled person and involves extreme difficulties in forming the desired tapered threaded portion with high accuracy and therefore in improving the efficiency.